Sickle Cell
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Sickle cell disease is a group of inherited red blood cell disorders. The most common type is known as sickle cell anemia. Normal red blood cells are round and flexible, allowing them to move easily through your blood vessels. But in sickle cell disease, an abnormal form of hemoglobin causes red blood cells to become stiff and sticky. These sickle-shaped cells can block blood flow, causing pain, tissue damage, and fatigue. Symptoms can vary from person to person, but can include pain, fatigue, shortness of breath, and frequent infections.
India has the second-highest burden of sickle cell disease in the world, particularly affecting tribal communities in India. Studies report have shown a carrier rate (sickle cell trait) ranging from 0% to as high as 40-55% depending on the specific community. While the disease can occur in any population, tribal communities have a much higher prevalence due to historical factors.
Breakdown of the affected communities:
- Central India: This region has the highest concentration, with communities like Pardhi, Bharia, Bhil, Gond, an
d Korku having a significant number of carriers and cases. - Western India: Tribal communities in Gujarat, Maharashtra, and Rajasthan also show a high prevalence. Examples include Warli, Koli, Dangi, and Halba communities.
- Southern India: Some southern states like Andhra Pradesh, Telangana, Karnataka,
and Tamil Nadu have tribal communities with a high sickle cell burden. These include Chenchu, Gond, and Particularly Vulnerable Tribal Groups (PVTGs).
Genetics of Sickle Cell
Sickle cell disease is caused by mutations in a specific gene called the HBB gene. This gene is located on chromosome 11 and provides instructions for making beta-globin, a protein that is a key component of hemoglobin.
- Mutation: The most common mutation in sickle cell disease is a single change in the DNA code of the HBB gene. This single change alters one amino acid (the building block of proteins) in the beta-globin protein.
- Hemoglobin S: This specific mutation creates an abnormal form of hemoglobin called hemoglobin S (HbS).
- Inheritance: Sickle cell disease is an autosomal recessive disorder. This means that a person needs to inherit two copies of the mutated gene, one from each parent, to develop the disease.
- Parents with one copy of the mutated gene (carriers) typically don't have sickle cell disease themselves.
- Children who inherit one normal HBB gene and one HbS gene have a condition called sickle cell trait. They are carriers but don't have the disease.
There is no cure for sickle cell disease, but there are treatments that can help manage the symptoms and improve quality of life.